Jet propulsion device for operation through fluid medium and method of operating it



June' 23, 1959 F. ZWICKY 2,891,381

JET PROPULSION DEVICE FOR OPERATION THROUGH FLUID MEDIUM AND METHOD OF OPERATING IT 4 SheetsSheet 1 Filed Oct. 11, 1944 IN VEN TOR. FR/ rz ZW/CKY BY cm A TTORA/? VS 2,891 ROUGH FLUID J1me 1959 F. ZWICKY ,381

JET PROPULSION DEVICE FOR OPERATION TH MEDIUM AND METHOD OF OPERATING 4 Sheets-Sheet 2 V Filed Oct. 11.1944

IN V EN TOR. FRITZ Z w/cm flTTOR/VEYS BY- CLm 9 2,891,381 THROUGH FLUID June 23, 1959 F. ZWICKY JET PROPULSION DEVICE FOR OPERATION MEDIUM AND METHOD OF OPERATING I 4 Sheets-Sheet 3 Filed 001;. 11, 1944 INVENTOR. FRITZ ZW/CKY BY v QM 9 ATTORNEYS June 23, 1959 F. 2 CKY 2,891,381 JET PROPULSION DEVICE F OPERATION THROUGH FLUID I MEDIUM AND METHOD OF OPERATING IT Filed 001;. 11, 1944 4 Sheets-Sheet 4 Fig.1!

x; v \Q w I i; \0' INVENTOR JET PROPULSION DEVICE FOR OPERATION TIHQOUGH FLUID MEDIUM AND METHOD OF OPERATING IT Fritz Zwicky, Pasadena, Calif., assignor, by mesne assignments, to Aerojet-General Corporation, Cincinnati, Ohio, a corporation of Ohio Application October 11, 1944, Serial No. 558,219 12 Claims. (Cl. 60-356) This invention relates to jet propulsion and particularly to devices propelled by jet propulsion through a fluid medium.

The principal object is to obtain eflicient andsustained operation of such jet propelled devices.

Devices have heretofore been proposed for jet propulsion through air or other fluid medium, and some of these have comprised a duct through which the fluid such as air from the medium has been introduced through an entrance opening, and caused to'react or burnwith a suitable fuel or chemical substance in the duct. The reaction or combustion has produced expanding gases which force the fluid together with the reaction products out through an exhaust nozzle at high velocity, thereby producing the propulsive force. 7 v

In my copending application, Serial No. 550,693, filed August 23, 1944, I have disclosed and claimed a device adapted to be operated by jet propulsion through a fluid medium by admitting fluid from the medium into a channel and exhausting it at higher velocity through an exhaust nozzle by the reaction of a suitable propellant or fuel within the channel.

According to my present invention I have improved on the prior known devices by the provision within the duct of a combustion chamber into which I inject a suitable fuel or fuel mixture separate from the main part of the duct through which most of the fluid from the medium is passing through the duct. -By this arrangement I am enabled to create an eflicient mixture of fuel which is not diluted prior to its combustion by the fluid from the medium. After combustion, the gases and heat from the combustion leave the combustion chamber and unite with the main body of fluid from the medium flowing through the duct increasing its energy and sending it on out the exhaust nozzle at higher velocity than the .intake velocity.

The invention is especially applicable .to jet propulsion devices operable in an air medium. When so used the major portion of the air entering the duct lay-passes .the combustion chamber and only a relatively small amount of the total air entering the duct is sent into the chamber to mix with the fuel. For example, this small amount of air may be sent through a suitable carburetor and mixed with a gasoline fuel or any other desired fuel and the mixture then sent into the combustion chamber in an. optimum ratio for combustion. By this means a relatively small amount of fuel is efficiently used to operate on the relatively large amount of air passing through the duct.

My invention is especially applicable to the use of fuels which create greater energy than gasoline and air mixtures. Aluminum borohydride (AI(BH lithium borohydride (LiBH the boron hydrides (B H B H B H9), zinc diethyl (Zn)C H and aluminum trimethyl (Al(Ch as such, or suspended in an inert liquid petroleum hydrocarbon such as gasoline or kerosene, for example, can be very effectively used with air for the purpose. The term borohydride is used in the specification and claims to designate any of the above I ited States Patent boron hydrides or metal borohydrides. Metal borohydrides and particularly aluminum borohydrides are discussed in The Journal of the American Chemical Society, vol. 62, page 3421, 1940, in an article by Schlesinger, Sanderson and Burg. Lithium borohydrides are particularly discussed in The Journal of the American Chemical Society, vol. 62, 3429, 1940, in an article by Schlesinger and Brown.

Another feature of my invention is the provision of a valve mechanism dividing into two portions the duct through which the main body of fluid flows so that when the products of the combustion are released into the rear portion the force of the explosion compresses the fluid therein and automatically closes the valve, which acts as a backstop against which the fluid is compressed to be released through the exhaust opening when the pressure generated by the explosion diminishes.

A related feature of my invention is the provision of an auxiliary starting means for bringing the device up to a speed at which snflicient intake of air can be had to produce sustained operation by its regular fuel combustion system.

The foregoing and other features of my invention will be better understood from the following detailed description and the accompanying drawings of which:

Fig. 1 is a longitudinal view showing a device in accordance with this invention;

Fig. 2 is an end view taken at the front end of Fig.1;

Fig. 3 is 'a longitudinal cross section view showing the fuel injectors for operation after the apparatus is in motion;

Fig. '4 is a longitudinal cross section view showing a device in accordance with this invention;

Fig. 5 is a cross section 'view taken on line 5-5 of Fig. 4 and showing the starting fuel injectors and the firing plugs;

Fig. 6 is a view partly in cross section taken on line 66 of Fig. 4;

Fig. T 7 is a broken cross section view taken on line 7-7 of Fig. 4;

Fig. ,8 shows a perspective view of the central valve blade;

Fig. 9 is a broken detail perspective view in cross section of part of the valve assembly embodied in the arrangement of Fig. 7;

Fig. 10 is a-broken detail view partly in cross section showing the valve body construction;

Fig. 11 is a longitudinal cross section View showing the arrangement of auxiliary firing chambers; and v Fig. 12 is a cross section view taken on line l212 of Fig. 11.

The device illustrated in Figs. 1 to 10 comprises a shell 1 forming a duct or passageway which is adapted to accommodate an air flow therethrough, the air entering at the mouth 7 and leaving at an exhaust nozzle 12. The shell 1 comprises leading section 2 which is preferably circular for about one-third its length from entrance 7 and then undergoes a gradual transistion to correspond to the rectangular portion of center section 3 as shown by the front end view Fig. 2. A square spacer frame 17 fits between sections 2 and 3. The rectangular portion of center section '3 tapers slightly from the front to a point just. beyond the center of the-section where it starts to undergo transition from .rectangular back to circular in order that it will correspond with the front end of circular tail section 4. Tail section 4 tapers toward the rear for about two-thirds of its length and from this point to the nozzle opening .12 the diameter increases slightly. Sections 2, 3 and 4 are bolted together by a series of bolts 5 and 6. Tail section 4 is provided with a series of radiation fins 8 to insure rapid cooling of the unit.

There is provided within the shell and in back of the mouth 7 a carburetor assembly 13. 'This comprises a' fuel and air mixing duct, or vestibule, 14 which is held in its central position by vanes 20 which are welded to duct, or vestibule, 14 and to the inner surface of member 2. A nose assembly slides into position at the front end of duct 14 and forms a Venturi-shaped tube or passage 15a (see Fig. 3). Section 15 is pushed into bore 34. Both sections 15 and bore 34 are finished to a close tolerance to insure a snug fit. The circumferential annular space 27 connects fuel feed conduits 28 with a plurality of circumferentially distributed fuel injectors 29. These injectors are mounted in section 15 at a suitable angle, preferably 45 degrees, and converge to a common center. To make the assembly leakproof, packing rings 26 are inserted in grooves 35 out in section 15.

Carburetor section 13 continues enlarging uniformly until the carburetor shell meets a blade valve assembly 36 which occupies the entire cross section area within the shell 1. The construction of blade valve assembly 36 is de scribed in detail with reference to Figs. 7, 8, 9 and 10. This valve is built up of an assembly of alternating flexible blades 72 and rigid channel members 71 as illustrated in Figs. 7, 8, 9 and 10. Each of the rigid channel members 71 comprises a rectangular-shaped plate 74, the upper face of which is provided with a curvature as shown in Figs. 9 and 10. The lower surface of the plates 74 are provided with a number of channels 77 formed by channel members 80 which are integral with the plate and run parallel with each other as shown. These channel partitions 80 taper in depth being deeper at leading edge 79 and tapering at the rear edge 83 to coincide with the thickness at the rear edge of the blade. The upper surface of members 71 is provided with a series of parallel ridges 84 corresponding with a number of channels and are positioned so as to be centered with reference to the respective channels.

In assembling the valve assembly 36 several flexible blades 72 are alternately interleaved between the several channel members 71 and are firmly held near their leading edge 73 between the channel strips 80 of one channel member and the front flat face 82 of the next. These valves and rigid channel members are held together by a series of bolts 85 which pass through holes 75 drilled in the blades and rigid channel members. When a series of these valves and channel members are installed to form the completed valve assembly 36 they completely fill the rectangular space just preceding firing chamber 40. For purpose of assembly these valves slide into a machined rectangular space 10 cut in the front end of firing chamber insert section 9 and are held in place by shoulder 16 and front section spacer 17. The arrangement of these valves in the valve receiver is shown by Fig. 7. Fig. 9 shows a perspective view illustrating one of the flexible blades 72 sandwiched between two adjacent channel members 71. Fig. 10 is a view looking up underneath channel members 71 and showing part of a blade valve 72. The curvature of the face 74 of each channel member is such that the rear edge 83 of each channel comes down to meet the rear edge 78 of the corresponding adjacent valve blades 72 as more clearly shown in Fig. 10. The arrangement is such that the lower edge 81 of all the channel partitions 80 of each channel member is flat against the flat surface of blade 72 as illustrated in Fig. 10. By this assembly arrangement the rear edges 78 of the flexible blades 72 are enabled to vibrate so as to alternately contact and move away from the rear edges 83 of the members 71. This creates the valve action as the valve is closed when blades 72 are against the members 71.

In order to enable that portion of the blades contiguous with the carburetor 13 to operate independently from the portion opening into duct area 38 surrounding the carburetor, all valve blades which come in contact with the circular area of carburetor chamber 14 are split by slots 76. The distance between these slots will vary depending on the portion of the carburetor circle intersected by the blades in such a manner that the blades near the top and bottom will have slots 76 close together while those which pass through the center of the carburetor will be slotted the maximum distance apart. It can readily be seen that this arrangement permits the valve blade section adjoining the inside of the carburetor chamber 14 to operate independently of that portion of the same blade which opens into the duct 38.

There is actually located within the shell 1 and coaxial with the carburetor chamber 14, a combustion chamber 40 held in place by vanes 31 attached to an insert section 9 to hold it in place. Insert section 9 is rectangularly shaped and slides into the square recms section 39, cut in center section 3. The insert 9 is clamped in position against shoulder 18 when section 2 and spacer 17 are bolted to section 3. The firing chamber 40 is cylindrical in shape preferably enlarging slightly toward the rear. Holes 42 are drilled into vanes 31 (see Fig. 5) just to the rear of the valve discharge and permit passage of injection tubes 43 whichare used in starting the ap-' paratus from rest. Another set of holes 37 are drilled rearwardly of the injection holes 43 to' permit insertion of spark plugs 41 into the combustion chamber 40.

A central deflector 44, preferably streamlined, is rigidly secured to the front end of tail section 4 by vanes 45. Deflector 44 extends into section 3 a suflicient distance to permit the front end 46 of deflector 44 to enter reaction chamber 40. A longitudinal axial hole 47 is bored into the rear end of deflector 44. This hole is threaded part way with threads 48 which receive rod 49. Rod 49 extends through the jet opening 12 and for a considerable distance outside the jet opening, the rod is threaded at its outside end. There is attached to the rod a member 50 in the shape of a pair of frusto-cones joined together at their base, as shown. This member 50 gradually enlarges to a maximum diameter and then tapers sharply. A hole 51 is drilled axially through member 50 and is made large enough to permit section 50 to slide on red 49. Hole 51 is enlarged for about two-thirds of the length from the rear, and the rear end is threaded to receive a bushing 52 which has threads cut on the outside to match the threads cut in closure member 50 and inside threads tapped into the central hole to thread on rod 49. Bushing 52 is locked in position by a nut 53. In the operation of the device, the gasoline or other fuel which may be used is supplied through pipe 28 and sprayed through the fuel injectors 29 into carburetor 13.

Before the device can operate by the combustion of this fuel supplied to the carburetor, a stream of incoming air from the mouth 7 must be caused to flow through the carburetor to carry the mixture of the injected fuel and air through the valves and into the combustion chamber 40 where they are ignited by the spark plugs. This could be accomplished in some suitable manner, for example, by placing the device in motion through the air at a suflicient rate to cause the necessary air stream to flow into the mouth and into the carburetor (and also through the outer ducts 38 and 54). This might be done, for example, by some auxiliary jet propulsion device operable during the starting time; or perhaps by placing some suitable fan at mouth 7 or in carburetor 13, operable during the starting time. The particular starting means which I have provided, however, are a set of auxiliary starting injectors 43 leading into the combustion chamber 40. The gasoline or other fuel is introduced under pressure by some suitable means (not shown) and injected into the reaction chamber 40, preferably intermittently, through the injector tubes 43. When the injection is intermittent a suitable timing device (not shown) for timing the period of intermittency may be used. The same or a similar timing device, (not shown) is used to control the firing period of the spark plug 41 in chamber 40; and

the timing of the spark plug should correspond with the timing of the fuel injections through auxiliary injectors 43. Each spark from the spark plug explodes the fuel in chamber 40, thereby raising the pressure in chamber 40 and closing the valves 32, and the energy of the explosion is transferred to the air in the duct which is then forced rearwardly out through the exhaust nozzle 12. If the pressure in the outer duct 54 exceeds the pressure of the air in duct 38, the outer valves 33 will also close at about the same time as the inner valves 32. The portion 33 of the valve mechanism between outer ducts 38 and 54, operates independently of the portion 32 between carburetor 13 and combustion chamber 40; so that the outer valve 33 may be open at the same time that the inner valve 32 is closed.

From the reaction force created at the exhaust nozzle from the series of intermittent explosions of the fuel in chamber 49 delivered by the auxiliary injector 43, the device gains forward speed. This causes incoming air at mouth 7 to flow through carburetor 13 and combustion chamber 40 and also through the outer ducts 33 and 54.

When the speed is sufiicient to establish a good flow of air into the mouth 7, the fuel through conduit 11 and fuel injector tubes 43 may be shut off and the fuel may then be turned on through the main supply pipe 28 to the carburetor, thereby spraying it into the carburetor. Preferably, the fuel flow through pipe 28 is continuous rather than intermittent. This mixture of fuel and air in the carburetor will thereby be sent through valve 32 each time the valve opens into chamber 40 where it will be fired intermittently in correspondence with the firing period. The spark plug will continue to fire the fuel mixture from the carburetor at the same rate at which it fired the fuel from the auxiliary starting source, and the opening and closing action of the valves will similarly continue. The major portion of the air from the mouth flows through the outer ducts 38 and 54 and joins the products of combustion from the combustion chamber in the region to the rear of the combustion chamber.

It will be understood that, if desired, the operation might be continued with the use of injectors 43 into the combustion chamber, without sending any fuel through injectors 29 into carburetor 13. Accordingly, it would in such a case be possible to omit injectors 29 or even to omit the entire carburetor l3. Ordinarily, however, it is preferable to run the device with the fuel injections into the carburetor instead of directly into the combustion chamber as the carburetor provides a better combustible mixture.

The force of the explosion as well as the heat and gases generated by the reaction are transmitted at chamber 30 to the large body of incoming air passing through the outer ducts 38 and 54, thereby transferring a major portion of the available energy of combustion to an extremely large mass of air as compared to the small volume of fuel used. Forward thrust is generated due to the fact that the air plus the combustion products are exhausted through the rear nozzle 12 at a velocity greater than that at which they enter the mouth 7. Furthermore, the heat generated by the combustion is transmitted through the firing chamber walls and vanes to the incoming mass of fresh air. This heated air passes through the exhaust orifice 12 at a greater velocity than that at which it entered the mouth 7. Since this heating occurs during the entire cycle it has the effect of producing a continuous thrust which becomes augmented at each ignition.

When the pressure of the explosion escapes the combustion chamber it compresses the gases within the passageway. As a result the fluid which is in the duct surrounding the firing chamber and in the region between the valve and the exhaust end of the firing chamber is virtually trapped by the force of the explosion. Since this fluid is compressible, and since it is prevented from escaping forward by the closed valves, a considerable energy is stored in this fluid. When the force of the explosion is spent sufiiciently, this stored energy is returned to the system again providing a propulsive force during the period between explosions.

The process of thrust generation takes place in the following manner: Air enters the mouth 7 of the diffuser which lies between mouth 7 and the valve entrance and is adiabatically compressed until it approaches the stagnation pressure in duct 38 at the entrance of the valve 36. Stagnation pressure at moderate forward speeds in an incompressible medium is defined as:

=diffuser efficiency from the entrance to the valve; that is, the ratio of the increase in pressure, at a given velocity, in the region adjacent to the upstream side of the valve, above the pressure of the surrounding .medium to the increase in pressure, at the same velocity, in the region adjacent to the upstream side of the valve, above the pressure of the surrounding medium, which would have been attainable if the fluid flow in the duct had occurred without losses such as friction and turbulence.

P =the pressure of the fluid in the outside medium.

=density of the fluid medium.

u =velocity of the fluid in the outside medium relative to the propulsion device travelling through it.

For all speeds in cpmpressible mediums, stagnation pressure is defined as:

P =theideally possible stagnation pressure. P,'=the achieved stagnation pressure.

Thus for "7d s/= s and for For high efliciency it is desirable that flame propagation be very high in order that the highest pressure may be attained. As the pressure within the reaction chamber rises the valves are slammed shut and the expansion of the hot combustion gases in the combustion chamber will force the unburned air in the annular duct through the exit 12.

To approach high operating efliciency the ratio 5 of the mass of fuel to the sum of the mass of fuel, such as gasoline, plus the entire mass of air admitted through mouth 7, must be as small as possible, preferably, in the order of magnitude of 1:50 to 1210000. Again to operate efiiciently the ratio of gasoline to air within the combustion chamber should be preferably between 1:10 and 1:20. The preferred ratio used is 1:15.

The propulsion unit of my invention is capable, due to the double ducting feature, of making efficient use of energy generated by the combustion without subjecting the walls and apparatus to excessive temperatures and pressures. This is due to the fact that the heat and explosion are generated by a relatively small mass of fuel burned in the combustion chamber and this heat is immediately transformed into kinetic energy of a very large mass of air which is entering through the outer duct 38 and is passing through the inner duct 54. In addition, more efficient utilization of the energy is achieved by exploding the fuel-air mixture in a region of higher pressure than that of the surrounding fluid medium. This pressure (stagnation pressure) is attained by proper proportioning of the area at the entrance of the'valves to the area of the entry throat. The higher the ratio of the area at the valve entry to the throat area the higher will be the stagnation pressure.

In actual practice it is impossible to obtain maximum theoretical stagnation pressure because losses such as turbulence and friction greatly increase with the increase in size of the maximum area over the entry area. As a result the ultimate efficient design will be one that is capable of obtaining the highest stagnation pressure and still keep the resultant losses low. The preferable ratios of entry area to the maximum area at valve entrance are 1:2 and 1:3.

It will also be recognized that I may operate the propulsion unit by using higher energy fuels, or propellants in place of gasoline. These reactants require smaller amounts of material per unit thrust developed, and should be preferably spontaneously ignitable in air. When such a propellant is used, the propellant will be fed into the firing chamber 40 directly instead of passing through carburetor 13, and the gasoline injection system in the mouth of the carburetor will be shut ofif.

In some instances there may he wanted more take-off thrust than can be produced by the explosion inthe central firing chamber when operated by the auxiliary injectors. Such additional thrust may be provided for the take-off by some means such as by the use of assisted take-01f propellant units attached to the apparatus, or by the use of an apparatus embodying additional firing chambers such as those shown in Figs. 11 and 12. For this purpose, the firing chamber and vanes insert assembly 9 at the rear of valve 36 in Fig. 1 may be replaced by the insert assembly shown in Figs. 11 and 12 comprising a central firing chamber 90 supported by vanes 91 which are attached to insert shell 92 as in the previously described firing chamber insert section 9. Spark plugs 41 and fuel injectors 43 are provided in the firing chamber through holes 93 and 94 drilled in the vanes 91.

Located at the top and bottom center of the insert section 92 are two auxiliary semi-circular firing chambers 95 equipped with injectors 96 which are attached to the fuel feed line (not shown) and pressure system (not shown) and separate spark plug 97 for firing the mixture. Both spark and fuel injections are made intermittent and are regulated by some suitable means (not shown). When this modified apparatus is to be started the fuel feed system is turned on so that a combustible charge is introduced into both of the auxiliary firing chambers and the central firing chambers simultaneously. The mixtures in each chamber are exploded simultaneously thereby providing added thrust to the propulsion unit during the period when it is necessary to overcome the inertia of the craft to which it is attached. The air-fuel mixture Within these firing chambers may be a :1 to 20:1 air-gasoline mixture. In operating my apparatus I prefer to use a :1 air to fuel mixture.

After the apparatus has attained sufficient speed the injectors and current to the auxiliary firing chambers and the spark system may be disconnected permitting the apparatus to operate in the same manner as an apparatus which is not provided with auxiliary starting devices such as was described earlier in the application.

I claim:

1. A reaction propelled device adapted for propulsion through a fluid medium comprising an elongated passageway having an inlet opening and an exhaust nozzle, an automatically operable valve dividing the passageway into two parts and located between said inlet opening and exhaust nozzle, a smaller and shorter duct located within said passageway comprising a vestibule and a combustion chamber, said vestibule having an opening near the inlet opening in front of the valve to admit air into said combustion chamber and contacting the entrance of said valve, said combustion chamber adjoining said valve on the downstream side, means for introducing fuel into said combustion chamber and means for igniting the fuel in the chamber.

I 2. Apparatus according to claim 1 in which the portion of the automatic valve between the vestibule and the combustion chamber operates independently from the portion of the automatic valve controlling the area be tween the inner duct and the elongated passageway.

3. A reaction propelled device adapted for propulsion through air comprising an elongated passageway having an inlet opening and an exhaust nozzle, an automatically operable valve dividing the passageway into two parts and located between said inlet opening and exhaust nozzle, a smaller and shorter duct located within said passageway comprising a vestibule and a combustion chamber, said vestibule having an opening near the inlet opening in front of the valve to admit air into said combustion chamber and contacting the entrance side of said valve, said combustion chamber adjoining said valve on the downstream side, means for introducing fuel into the vestibule and means for firing the fuel-air mixture in the combustion chamber.

4. In an apparatus according to claim 3 an auxiliary starting means in the combustion chamber comprising a plurality of fuel injectors placed circumferentially in said combustion chamber, a fuel conduit connecting said injectors to said fuel source, means for placing said fuel under pressure, and means for igniting the fuel in said combustion chamber.

5. A reaction propelled device adapted for propulsion through air comprising an elongated passageway having an inlet opening and an exhaust nozzle, an automatically operable valve dividing the passageway, a smaller and shorter duct located within said passageway comprising a vestibule and a combustion chamber, said vestibule having an opening near the inlet of said passageway and extending to said valve, a constriction in said vestibule, a plurality of gasoline injectors for discharging gasoline into said vestibule, and means for firing the resulting gasoline-air mixture which enters the combustion chamber. 6. A reaction propelled device adapted for propulsion through air comprising an elongated passageway having an inlet opening and an exhaust nozzle, an automatically operable valve dividing the passageway in two parts, a smaller and shorter duct located within said passageway comprising a vestibule and a main combustion chamber through which flow is controlled by said automatic valve independently of the flow through the main duct, auxiliary combustion chambers located in the duct space between said main combustion chamber and the wall of the elongated passageway, the front of all combustion chambers being adjacent to the discharge side of said automatic valve, means for introducing fuel into each combustion chamber and means for igniting the fuel in said chambers.

7. A reaction propelled device adapted for propulsion through air comprising an elongated passageway having a forward inlet opening and a rear exhaust nozzle, a duct longitudinally disposed in the passageway, said duct being divided transversely into a vestibule and a combustion chamber and being open at both ends, means for controlling fluid flow through the duct from the vestibule to the combustion chamber independently of fluid flow through the surrounding passageway, said last named means being operable to prevent substantial fluid flow from the combustion chamber to the vestibule, means for introducing fuel to the vestibule and means for igniting a combustible mixture within the combustion chamber.

8. A reaction propelled device adapted for propulsion through air comprising an elongated passageway having a forward inlet opening and a rear exhaust nozzle, a duct longitudinally disposed within the passageway, said duct being divided transversely into a vestibule and a combustion chamber and being open at both ends, independent means dividing said passageway transversely into two sections and operable to prevent substantial fluid flow from the rear to the forward section, means for controlling fluid flow through the duct from the vestibule to the combustion chamber independently of fluid flow through the surrounding passageway, said last named means being operable to prevent substantial fluid flow from the combusion chamber to the vestibule, means for introducing fuel to the vestibule and means for igniting a combustible mixture within the combustion chamber.

9. A reaction propelled device adapted for propulsion through air comprising an elongated passageway open at the forward end to permit entry of air when the device is propelled through air and open at the rear end to permit fluid exhaust, a mixing chamber and a combustion chamber disposed within the passageway, an exhaust opening from the mixing chamber juxtaposed adjacent an entrance opening into the combustion chamber, an automatically operable valve situated between the two openings and operable to allow fluid to flow from the mixing chamber to the combusion chamber but substantially preventing fluid from flowing from the combustion chamber to the mixing chamber, said mixing chamber having an entrance opening to permit entry therein of a portion of the air entering the forward end of said elongated member, and means for injecting a combustible fuel into said mixing chamber to mix with the air introduced therein and to pass therefrom into said combustion chamber and means for periodically combusting an air-fuel mixture in said combustion chamber.

10. A reaction propelled device adapted for propulsion through a fluid medium comprising an elongated passageway having an inlet opening and exhaust nozzle, an automatically operable valve dividing the passageway into two parts and located between said inlet opening and exhaust nozzle, a smaller and shorter duct comprising a vestibule and combustion chamber separated by an automatically operable valve, said vestibule having an inlet opening adjacent the inlet opening of the passageway and said combustion chamber having an exhaust opening adjacent the exhaust nozzle of the passage way, means for introducing fuel into said combustion chamber and means for igniting the fuel in the chamber.

11. An apparatus according to claim wherein the duct is so positioned in the device with relation to the passageway so that a portion of the heat of combustion is transferred from the combustion chamber walls to the fluid flowing through the passageway.

12. The method of producing thrust by reaction in a propulsion thrust motor which comprises admitting air into the forward end of the motor, mixing a portion of the air thus admitted with a combustible fuel in a carburetion zone, introducing the air-fuel mixture into a combustion zone while by-passing the remaining portion of the air around the carburetion and combustion zones, periodically combusting the air-fuel mixture in the combustion zone while preventing its return to the carburetion zone, transferring at least a portion of the heat of combustion from the combusted mixture to the admitted air which is unmixed, while preventing its return to the forward end of the motor, commingling the products of combustion with said unmixed air after said unmixed air has absorbed said portion of the heat of combustion, and exhausting the resultant mixture of air and combustion products from the rear of the motor.

References Cited in the file of this patent UNITED STATES PATENTS 1,021,521 Hroult Mar. 26, 1912 1,305,340 Bostedo June 3, 1919 1,369,672 Koenig Feb. 22, 1921 1,517,422 Hall Dec. 2, 1924 2,024,274 Campini Dec. 17, 1935 2,312,605 Traupel Mar. 2, 1943 2,335,005 Gieskieng et a1. Nov. 23, 1943 2,409,176 Allen Oct. 15, 1946 FOREIGN PATENTS 863,928 France Jan. 6, 1941 640,228 Germany Dec. 28, 1936 OTHER REFERENCES Journal of the American Chemical Society, vol. 62, 1940, pages 3421, 3429. 

